Merge branch 'master' into master

CONTRIBUTING.md

@@ -0,0 +1,84 @@
+# Contributing guidelines
+
+## Before contributing
+
+Welcome to [TheAlgorithms/Javascript](https://github.com/TheAlgorithms/Javascript)! Before sending your pull requests, make sure that you **read the whole guidelines**. If you have any doubt on the contributing guide, please feel free to [state it clearly in an issue](https://github.com/TheAlgorithms/Javascript/issues/new)
+
+## Contributing
+
+### Contributor
+
+We are very happy that you consider implementing algorithms and data structure for others! This repository is referenced and used by learners from around the globe. Being one of our contributors, you agree and confirm that:
+
+- You did your work - plagiarism is not allowed.
+  - Any plagiarized work will not be merged.
+- Your work will be distributed under [GNU License](License) once your pull request is merged
+- You submitted work fulfils or mostly fulfils our styles and standards
+
+**New implementation** is welcome! For example, new solutions to a problem, different representations of a graph data structure or algorithm designs with different complexity.
+
+**Improving comments** and **writing proper tests** are also highly welcome.
+
+### Contribution
+
+We appreciate any contribution, from fixing grammar mistakes to implementing complex algorithms. Please read this section if you are contributing your work.
+
+
+If you submit a pull request that resolves an open issue, please help us to keep our issue list small by adding `fixes: #{$ISSUE_NO}` to your commit message. GitHub will use this tag to auto close the issue if your PR is merged.
+
+#### What is an Algorithm?
+
+An Algorithm is one or more functions (or classes) that:
+* take one or more inputs,
+* perform some internal calculations or data manipulations,
+* return one or more outputs,
+* have minimal side effects.
+
+Algorithms should be packaged in a way that would make it easy for readers to put them into larger programs.
+
+Algorithms should:
+* have intuitive class and function names that make their purpose clear to readers
+* use JavaScript naming conventions and intuitive variable names to ease comprehension
+* be flexible to take different input values
+* raise JavaScript exceptions (RangeError, etc.) on erroneous input values
+
+Algorithms in this repo should not be how-to examples for existing JavaScript packages.  Instead, they should perform internal calculations or manipulations to convert input values into different output values.  Those calculations or manipulations can use data types, classes, or functions of existing JavaScript packages but each algorithm in this repo should add unique value.
+
+#### Coding Style
+
+To maximize the readability and correctness of our code, we require that new submissions follow [JavaScript Standard Style](https://standardjs.com/)
+  - Command to  install JavaScript Standard Style
+    ```
+    $ npm install standard --save-dev
+    ```
+  - Usage
+    ```
+    $ standard MyFile.js  // if that fails, try: npx standard MyFile.js
+    ```
+
+- Use camelCase for with leading character lowercase for identifier names (variables and functions)
+- Names start with a letter
+- follow code indentation
+  - Always use 2 spaces for indentation of code blocks
+    ```
+	function sumOfArray (arrayOfNumbers) {
+	    let sum = 0
+	    for (let i = 0; i < arrayOfNumbers.length; i++) {
+	      sum += arrayOfNumbers[i]
+	    }
+	    return (sum)
+	  }
+
+	```
+- Avoid using global variables and avoid '=='
+- Please use 'let' over 'var'
+- We strongly recommend the use of ECMAScript 6
+- Avoid importing external libraries for basic algorithms. Only use those libraries for complicated algorithms.
+
+
+
+- Most importantly,
+  - **Be consistent in the use of these guidelines when submitting.**
+  - Happy coding!
+
+Writer [@itsvinayak](https://github.com/itsvinayak), May 2020.

Data Structures/Linked List/DoublyLinkedList.js

@@ -1,195 +1,198 @@
-// Hamza chabchoub contribution for a university project
+//Hamza chabchoub contribution for a university project 
-function doubleLinkedList () {
+function doubleLinkedList() {
-  const Node = function (element) {
+    let Node = function(element) {
-    this.element = element
+      this.element = element;
-    this.next = null
+      this.next = null;
-    this.prev = null
+      this.prev = null;
-  }
-
-  let length = 0
-  let head = null
-  let tail = null
-
-  // Add new element
-  this.append = function (element) {
-    const node = new Node(element)
-
-    if (!head) {
-      head = node
-      tail = node
-    } else {
-      node.prev = tail
-      tail.next = node
-      tail = node
     }
     
-    length++
+    let length = 0;
-  }
+    let head = null;
+    let tail = null;
     
-  // Add element
+    //Add new element
-  this.insert = function (position, element) {
+    this.append = function(element) {
-    // Check of out-of-bound values
+      let node = new Node(element);
-    if (position >= 0 && position <= length) {
-      const node = new Node(element)
-      let current = head
-      let previous
-      let index = 0
       
-      if (position === 0) {
+      if(!head){
-        if (!head) {
+            head = node;
-          head = node
+            tail = node;
-          tail = node
+       }else{
-        } else {
+         node.prev = tail;
-          node.next = current
+         tail.next = node;
-          current.prev = node
+         tail = node;
-          head = node
+       }
-        }
+      
-      } else if (position === length) {
+      length++;
-        current = tail
+    }
-        current.next = node
+    
-        node.prev = current
+    
-        tail = node
+    //Add element 
-      } else {
+    this.insert = function(position, element) {
-        while (index++ < position) {
+      
-          previous = current
+      //Check of out-of-bound values
-          current = current.next
+      if(position >= 0 && position <= length){
+        let node = new Node(element),
+            current = head,
+            previous,
+            index = 0;
+        
+        if(position === 0){
+          if(!head){
+            head = node;
+            tail = node;
+          }else{
+            node.next = current;
+            current.prev = node;
+            head = node;
+          }
+        }else if(position === length){
+          current = tail;
+          current.next = node;
+          node.prev = current;
+          tail = node;
+        }else{
+          while(index++ < position){
+            previous = current;
+            current = current.next;
+          }
+          
+          node.next = current;
+          previous.next = node;
+          
+          //New
+          current.prev = node;
+          node.prev = previous; 
         }
         
-        node.next = current
+        length++;
-        previous.next = node
+        return true;
+      }else{
+        return false;
+      }
+    }
     
-        // New
+    //Remove element at any position
-        current.prev = node
+    this.removeAt = function(position){
-        node.prev = previous
+      //look for out-of-bounds value
+      if(position > -1 && position < length){
+        let current = head, previous, index = 0;
+        
+        //Removing first item
+        if(position === 0){
+          head = current.next;
+          
+          //if there is only one item, update tail //NEW
+          if(length === 1){
+            tail = null;
+          }else{
+            head.prev = null;
+          }
+        }else if(position === length - 1){
+          current = tail;
+          tail = current.prev;
+          tail.next = null;
+        }else{
+          while(index++ < position){
+            previous = current;
+            current = current.next;
+          }
+          
+          //link previous with current's next - skip it
+          previous.next = current.next; 
+          current.next.prev = previous;
+        }
+        
+        length--;
+        return current.element;
+      }else{
+        return null;
+      }
+    }
+    
+    //Get the indexOf item 
+    this.indexOf = function(elm){
+      let current = head,
+      index = -1;
+  
+      //If element found then return its position
+      while(current){
+        if(elm === current.element){
+           return ++index;
+        }
+  
+         index++;
+         current = current.next;
+       }
+  
+      //Else return -1
+      return -1;
+    };
+    
+    //Find the item in the list
+    this.isPresent = (elm) => {
+      return this.indexOf(elm) !== -1;
+    };
+    
+    //Delete an item from the list
+    this.delete = (elm) => {
+       return this.removeAt(this.indexOf(elm));
+    };  
+    
+    //Delete first item from the list
+    this.deleteHead = function(){
+      this.removeAt(0);
+    }
+    
+    //Delete last item from the list
+    this.deleteTail = function(){
+      this.removeAt(length-1);
+    }
+    
+    //Print item of the string
+    this.toString = function(){
+      let current = head,
+      string = '';
+  
+      while(current){
+        string += current.element + (current.next ? '\n' : '');
+        current = current.next;
       }
   
-      length++
+      return string;
-      return true
+    };
-    } else {
-      return false
-    }
-  }
     
-  // Remove element at any position
+    //Convert list to array
-  this.removeAt = function (position) {
+    this.toArray = function(){
-    // look for out-of-bounds value
+      let arr = [],
-    if (position > -1 && position < length) {
+      current = head;
-      let current = head; let previous; let index = 0
   
-      // Removing first item
+      while(current){
-      if (position === 0) {
+        arr.push(current.element);
-        head = current.next
+        current = current.next;
-
-        // if there is only one item, update tail //NEW
-        if (length === 1) {
-          tail = null
-        } else {
-          head.prev = null
-        }
-      } else if (position === length - 1) {
-        current = tail
-        tail = current.prev
-        tail.next = null
-      } else {
-        while (index++ < position) {
-          previous = current
-          current = current.next
-        }
-
-        // link previous with current's next - skip it
-        previous.next = current.next
-        current.next.prev = previous
       }
   
-      length--
+      return arr;
-      return current.element
+    };
-    } else {
+    
-      return null
+    //Check if list is empty
+    this.isEmpty = function(){
+      return length === 0;
+    };
+    
+    //Get the size of the list
+    this.size = function(){
+      return length;
+    }
+    
+    //Get the head
+    this.getHead = function() {
+      return head;
+    }
+    
+    //Get the tail
+    this.getTail = function() {
+      return tail;
     }
   } 
 
-  // Get the indexOf item
-  this.indexOf = function (elm) {
-    let current = head
-    let index = -1
-
-    // If element found then return its position
-    while (current) {
-      if (elm === current.element) {
-        return ++index
-      }
-
-      index++
-      current = current.next
-    }
-
-    // Else return -1
-    return -1
-  }
-
-  // Find the item in the list
-  this.isPresent = (elm) => {
-    return this.indexOf(elm) !== -1
-  }
-
-  // Delete an item from the list
-  this.delete = (elm) => {
-    return this.removeAt(this.indexOf(elm))
-  }
-
-  // Delete first item from the list
-  this.deleteHead = function () {
-    this.removeAt(0)
-  }
-
-  // Delete last item from the list
-  this.deleteTail = function () {
-    this.removeAt(length - 1)
-  }
-
-  // Print item of the string
-  this.toString = function () {
-    let current = head
-    let string = ''
-
-    while (current) {
-      string += current.element + (current.next ? '\n' : '')
-      current = current.next
-    }
-
-    return string
-  }
-
-  // Convert list to array
-  this.toArray = function () {
-    const arr = []
-    let current = head
-
-    while (current) {
-      arr.push(current.element)
-      current = current.next
-    }
-
-    return arr
-  }
-
-  // Check if list is empty
-  this.isEmpty = function () {
-    return length === 0
-  }
-
-  // Get the size of the list
-  this.size = function () {
-    return length
-  }
-
-  // Get the head
-  this.getHead = function () {
-    return head
-  }
-
-  // Get the tail
-  this.getTail = function () {
-    return tail
-  }
-}

Sorts/TopologicalSort.js

@@ -1,58 +1,60 @@
-function TopologicalSorter () {
-  var graph = {}
-  var isVisitedNode
-  var finishTimeCount
-  var finishingTimeList
-  var nextNode
 
-  this.addOrder = function (nodeA, nodeB) {
+function TopologicalSorter() {
-    nodeA = String(nodeA)
+    var graph = {},
-    nodeB = String(nodeB)
+        isVisitedNode,
-    graph[nodeA] = graph[nodeA] || []
+        finishTimeCount,
-    graph[nodeA].push(nodeB)
+        finishingTimeList,
-  }
+        nextNode;
 
-  this.sortAndGetOrderedItems = function () {
+    this.addOrder = function (nodeA, nodeB) {
-    isVisitedNode = Object.create(null)
+        nodeA = String(nodeA);
-    finishTimeCount = 0
+        nodeB = String(nodeB);
-    finishingTimeList = []
+        graph[nodeA] = graph[nodeA] || [];
-
+        graph[nodeA].push(nodeB);
-    for (var node in graph) {
-      if (graph.hasOwnProperty(node) && !isVisitedNode[node]) {
-        dfsTraverse(node)
-      }
     }
     
-    finishingTimeList.sort(function (item1, item2) {
+    this.sortAndGetOrderedItems = function () {
-      return item1.finishTime > item2.finishTime ? -1 : 1
+        isVisitedNode = Object.create(null);
-    })
+        finishTimeCount = 0;
+        finishingTimeList = [];
 
-    return finishingTimeList.map(function (value) { return value.node })
+        for (var node in graph) {
-  }
+            if (graph.hasOwnProperty(node) && !isVisitedNode[node]) {
+                dfsTraverse(node);
+            }
+        }
 
-  function dfsTraverse (node) {
+        finishingTimeList.sort(function (item1, item2) {
-    isVisitedNode[node] = true
+            return item1.finishTime > item2.finishTime ? -1 : 1;
-    if (graph[node]) {
+        });
-      for (var i = 0; i < graph[node].length; i++) {
+
-        nextNode = graph[node][i]
+        return finishingTimeList.map(function (value) { return value.node })
-        if (isVisitedNode[nextNode]) continue
-        dfsTraverse(nextNode)
-      }
     }
 
-    finishingTimeList.push({
+    function dfsTraverse(node) {
-      node: node,
+        isVisitedNode[node] = true;
-      finishTime: ++finishTimeCount
+        if (graph[node]) {
-    })
+            for (var i = 0; i < graph[node].length; i++) {
-  }
+                nextNode = graph[node][i];
+                if (isVisitedNode[nextNode]) continue;
+                dfsTraverse(nextNode);
+            }
+        }
+
+        finishingTimeList.push({
+            node: node,
+            finishTime: ++finishTimeCount
+        });
+    }
 }
 
+
 /* TEST */
-var topoSorter = new TopologicalSorter()
+var topoSorter = new TopologicalSorter();
-topoSorter.addOrder(5, 2)
+topoSorter.addOrder(5, 2);
-topoSorter.addOrder(5, 0)
+topoSorter.addOrder(5, 0);
-topoSorter.addOrder(4, 0)
+topoSorter.addOrder(4, 0);
-topoSorter.addOrder(4, 1)
+topoSorter.addOrder(4, 1);
-topoSorter.addOrder(2, 3)
+topoSorter.addOrder(2, 3);
-topoSorter.addOrder(3, 1)
+topoSorter.addOrder(3, 1);
-console.log(topoSorter.sortAndGetOrderedItems())
+console.log(topoSorter.sortAndGetOrderedItems());

maths/DijkstraSmallestPath.js

@@ -1,66 +1,71 @@
 // starting at s
-function solve (graph, s) {
+function solve(graph, s) {
-  var solutions = {}
+  var solutions = {};
-  solutions[s] = []
+  solutions[s] = [];
-  solutions[s].dist = 0
+  solutions[s].dist = 0;
   
-  while (true) {
+  while(true) {
-    var p = null
+    var p = null;
-    var neighbor = null
+    var neighbor = null;
-    var dist = Infinity
+    var dist = Infinity;
     
-    for (var n in solutions) {
-      if (!solutions[n]) { continue }
-      var ndist = solutions[n].dist
-      var adj = graph[n]
     
-      for (var a in adj) {
+    for(var n in solutions) {
-        if (solutions[a]) { continue }
+      if(!solutions[n])
+        continue
+      var ndist = solutions[n].dist;
+      var adj = graph[n];
   
-        var d = adj[a] + ndist
+      for(var a in adj) {
-        if (d < dist) {
+
-          p = solutions[n]
+        if(solutions[a])
-          neighbor = a
+          continue;
-          dist = d
+       
+        var d = adj[a] + ndist;
+        if(d < dist) {
+   
+          p = solutions[n];
+          neighbor = a;
+          dist = d;
         }
       }
     }
     
-    // no more solutions
+    //no more solutions
-    if (dist === Infinity) {
+    if(dist === Infinity) {
-      break
+        break;
     }
     
-    // extend parent's solution path
+    //extend parent's solution path
-    solutions[neighbor] = p.concat(neighbor)
+    solutions[neighbor] = p.concat(neighbor);
-    // extend parent's cost
+    //extend parent's cost
-    solutions[neighbor].dist = dist
+    solutions[neighbor].dist = dist;
   }
   
-  return solutions
+  return solutions;
 }
-// create graph
+//create graph
-var graph = {}
+var graph = {};
 
 var layout = {
-  R: ['2'],
+  'R': ['2'],
-  2: ['3', '4'],
+  '2': ['3','4'],
-  3: ['4', '6', '13'],
+  '3': ['4','6','13'],
-  4: ['5', '8'],
+  '4': ['5','8'],
-  5: ['7', '11'],
+  '5': ['7','11'],
-  6: ['13', '15'],
+  '6': ['13','15'],
-  7: ['10'],
+  '7': ['10'],
-  8: ['11', '13'],
+  '8': ['11','13'],
-  9: ['14'],
+  '9': ['14'],
-  10: [],
+  '10': [],
-  11: ['12'],
+  '11': ['12'],
-  12: [],
+  '12': [],
-  13: ['14'],
+  '13': ['14'],
-  14: [],
+  '14': [],
-  15: []
+  '15': []
 }
 
-// convert uni-directional to bi-directional graph
+//convert uni-directional to bi-directional graph
 // var graph = {
 //     a: {e:1, b:1, g:3},
 //     b: {a:1, c:1},
@@ -72,25 +77,27 @@ var layout = {
 //     h: {f:1}
 // };
 
-for (var id in layout) {
+for(var id in layout) {
-  if (!graph[id]) { graph[id] = {} }
+  if(!graph[id])
-  layout[id].forEach(function (aid) {
+    graph[id] = {};
-    graph[id][aid] = 1
+  layout[id].forEach(function(aid) {
-    if (!graph[aid]) { graph[aid] = {} }
+    graph[id][aid] = 1;
-    graph[aid][id] = 1
+    if(!graph[aid])
-  })
+      graph[aid] = {};
+    graph[aid][id] = 1;
+  });
 }
 
-// choose start node
+//choose start node
-var start = '10'
+var start = '10';
-// get all solutions
+//get all solutions
-var solutions = solve(graph, start)
+var solutions = solve(graph, start);
 
-console.log("From '" + start + "' to")
+console.log("From '"+start+"' to");
-// display solutions
+//display solutions
-for (var s in solutions) {
+for(var s in solutions) {
-  if (!solutions[s]) continue
+  if(!solutions[s]) continue;
-  console.log(' -> ' + s + ': [' + solutions[s].join(', ') + ']   (dist:' + solutions[s].dist + ')')
+  console.log(" -> " + s + ": [" + solutions[s].join(", ") + "]   (dist:" + solutions[s].dist + ")");
 }
 
 // From '10' to

maths/graph.js

@@ -1,82 +1,87 @@
 // create a graph class 
 class Graph { 
-  // defining vertex array and
+    // defining vertex array and 
-  // adjacent list
+    // adjacent list 
-  constructor (noOfVertices) {
+    constructor(noOfVertices) 
-    this.noOfVertices = noOfVertices
+    { 
-    this.AdjList = new Map()
+        this.noOfVertices = noOfVertices; 
-  }
+        this.AdjList = new Map(); 
+    } 
   
-  // functions to be implemented
+    // functions to be implemented 
   
-  // addVertex(v)
+    // addVertex(v) 
-  // addEdge(v, w)
+    // addEdge(v, w) 
-  // printGraph()
+    // printGraph() 
   
-  // bfs(v)
+    // bfs(v) 
-  // dfs(v)
+    // dfs(v) 
 }
 
 // add vertex to the graph 
 addVertex(v) 
 { 
-  // initialize the adjacent list with a
+    // initialize the adjacent list with a 
-  // null array
+    // null array 
-  this.AdjList.set(v, [])
+    this.AdjList.set(v, []); 
 }
 
 // add edge to the graph 
 addEdge(v, w) 
 { 
-  // get the list for vertex v and put the
+    // get the list for vertex v and put the 
-  // vertex w denoting edge between v and w
+    // vertex w denoting edge between v and w 
-  this.AdjList.get(v).push(w)
+    this.AdjList.get(v).push(w); 
   
-  // Since graph is undirected,
+    // Since graph is undirected, 
-  // add an edge from w to v also
+    // add an edge from w to v also 
-  this.AdjList.get(w).push(v)
+    this.AdjList.get(w).push(v); 
 } 
 
+
 // Prints the vertex and adjacency list 
 printGraph() 
 { 
-  // get all the vertices
+    // get all the vertices 
-  var get_keys = this.AdjList.keys()
+    var get_keys = this.AdjList.keys(); 
   
-  // iterate over the vertices
+    // iterate over the vertices 
-  for (var i of get_keys) {
+    for (var i of get_keys)  
-    // great the corresponding adjacency list
+{ 
-    // for the vertex
+        // great the corresponding adjacency list 
-    var get_values = this.AdjList.get(i)
+        // for the vertex 
-    var conc = ''
+        var get_values = this.AdjList.get(i); 
+        var conc = ""; 
   
-    // iterate over the adjacency list
+        // iterate over the adjacency list 
-    // concatenate the values into a string
+        // concatenate the values into a string 
-    for (var j of get_values) { conc += j + ' ' }
+        for (var j of get_values) 
+            conc += j + " "; 
   
-    // print the vertex and its adjacency list
+        // print the vertex and its adjacency list 
-    console.log(i + ' -> ' + conc)
+        console.log(i + " -> " + conc); 
-  }
+    } 
 }
 
+
 // Example
-var graph = new Graph(6)
+var graph = new Graph(6); 
-var vertices = ['A', 'B', 'C', 'D', 'E', 'F']
+var vertices = [ 'A', 'B', 'C', 'D', 'E', 'F' ]; 
   
 // adding vertices 
 for (var i = 0; i < vertices.length; i++) { 
-  g.addVertex(vertices[i])
+    g.addVertex(vertices[i]); 
 } 
   
 // adding edges 
-g.addEdge('A', 'B')
+g.addEdge('A', 'B'); 
-g.addEdge('A', 'D')
+g.addEdge('A', 'D'); 
-g.addEdge('A', 'E')
+g.addEdge('A', 'E'); 
-g.addEdge('B', 'C')
+g.addEdge('B', 'C'); 
-g.addEdge('D', 'E')
+g.addEdge('D', 'E'); 
-g.addEdge('E', 'F')
+g.addEdge('E', 'F'); 
-g.addEdge('E', 'C')
+g.addEdge('E', 'C'); 
-g.addEdge('C', 'F')
+g.addEdge('C', 'F'); 
   
 // prints all vertex and 
 // its adjacency list 
@@ -86,4 +91,5 @@ g.addEdge('C', 'F')
 // D -> A E 
 // E -> A D F C 
 // F -> E C 
-g.printGraph()
+g.printGraph(); 
+